# Civil Engineering - Theory of Structures - Discussion

### Discussion :: Theory of Structures - Section 1 (Q.No.28)

28.

A rolled steel joist is simply supported at its ends and carries a uniformly distributed load which causes a maximum deflection of 10 mm and slope at the ends of 0.002 radian. The length of the joist will be,

 [A]. 10 m [B]. 12 m [C]. 14 m [D]. 16 m [E]. 18 m

Explanation:

No answer description available for this question.

 Suhasini said: (Feb 3, 2015) Max deflection = 5wL4/384EI. Slope = wL3/24EI. w = 24EI*slope/L3. Max deflection = 5*(24EI*slope)*L4/(L3*384EI). Therefore, L = max deflection*16/(5*Slope). = 10*16/(5*0.002) = 16000 mm = 16 m.

 Chhaya said: (Oct 5, 2017) Thanks @Suhasini.

 Asay said: (Nov 21, 2017) Deflection=5wl^4/384EI=10mm. =====> EI=5wl^4/384*10 -----> (1) Slope=wl^3/24EI=0.002mm =====> EI=wl^3/24*0.002 -----> (2) Comparing eq (1) & (2) 5wl^4/384*10=wl^3/24*0.002 l=384*10/5*24*0.002 l=384*10*1000/5*24*2 l=16*1000mm l=16m. So , The length of the joist will be =16m (Option D) is correct Answer.

 Pawan said: (Jun 16, 2019) Thanks @Suhasini.